My husband and I have lived on our earthen floor for a few years now, and have had almost the same
experience as Ardilla.
The oil finishing process is so key. Straight linseed oil on the first coat, and slowly more and more orange oil solvent added with additional layers. Hardwood floor finish is an interesting idea. I know many folks choose to wax also.
With adequate oil, though, the floor will actually NOT get scratched even with a wire brush. I've tried. The reason I tried is because I have had to patch the floor in a couple areas.
During periods of high humidity and hot weather (I'm in
Arkansas) the floor will soften to the point that if a person sits in a chair with pointy legs for too long, the floor will dent. When I tried to dig out the dent and abrade the adjacent floor, I found I could chisel through the oil layer, but nothing but nothing would abrade it. It took the sand right off of sandpaper. Quite impressive really.
I had thought if I could abrade the oil layer off of the area surrounding the patch, I'd be able to blend the new patch in better. But instead, I settled for washing any
cob smears off of the adjacent oiled floor and oiling the patch to match. As long as I burnished a few times during the drying process, I was able to prevent any cracking between old and new and the result looks good to me.